Microbiology Chapter 26

Cold is preferred for storing food because it retards microbial growth by slowing down metabolic processes. A. True B. False

A. True

Which of these microbial products is needed to produce "gasohol"? A. methanol B. citric acid C. ethanol D. aspartame E. hyaluronidase

C. ethanol

What is the acceptable level of coliform bacteria per 100 ml of drinking water? A. 0 B. 10 C. 100 D. 200

A. 0 Although it is acceptable to have some coliform bacteria present in recreational waters, it is not acceptable to have any coliforms in drinking water because of their ability to cause serious intestinal disease.

Reducing the water content of food is a highly effective way of reducing food spoilage. A. True B. False

A. True

Without the activities of microorganisms, the functioning of the Earth's ecosystems would cease. A. True B. False

A. True

Alexis's group presentation on the benefits of microbes is a success, and her group earns an "A" for the project. The last few weeks of the course focus on industrial microbiology. Industrial microbiology began as large-scale food fermentations, specifically for dairy products and alcoholic beverages such as those mentioned previously. As technology progressed, so did the number of products that came to be made on a large scale. Today, industrial microbiology applies the idea of biotechnology to produce commercially valuable substances. Which of the following are examples of commercial microbial products? Select all that apply A. antibiotics, vaccines, and steroids B. glutamic acid, lysine, methionine, and phenylalanine C. baker's yeast, Rhizobium, and Bt-toxin D. amylase, glucose isomerase, proteases, and rennin

A. antibiotics, vaccines, and steroids B. glutamic acid, lysine, methionine, and phenylalanine C. baker's yeast, Rhizobium, and Bt-toxin D. amylase, glucose isomerase, proteases, and rennin The ability to produce massive quantities of all of the items listed has been a success for biotechnology. In industrial microbiology, certain strains of microorganisms are chosen based on the products they form during natural processes or on their ability to be genetically engineered to produce something they may not naturally make. The microbes are grown in large vessels with very specific controls for environmental factors such as aeration, pH, and temperature. The microbes produce the substance that is later harvested and purified for distribution to the consumer. Biotechnology has great potential for the future of alternative energy sources and biofuels, which could reduce our dependence on oil and other fossil fuels.

Alum is a chemical necessary for which of the following stages of drinking water treatment? A. flocculation B. sedimentation C. filtration D. disinfection

A. flocculation Alum, or aluminum potassium sulfate, joins with suspended particles and microorganisms in water to form large aggregates called flocs, which settle to the bottom of the treatment tank.

Molecular data analysis supports Jamie's initial identification of a novel Archaean species. Jamie further classifies this organism as a hyperthermophile capable of growth near the hydrothermal vent because it has symbiotic relationships with chemoautotrophic bacteria. These bacteria receive their energy from hydrogen sulfide and support the growth of other organisms. Which of the following situations is an example of a symbiotic relationship? Select all that apply. A. fungi growing on the root hairs of plants B. Haemophilus influenzae growing in the respiratory tract C. E. coli growing in the large intestine of humans D. Staphylococcus epidermidis growing on the skin

A. fungi growing on the root hairs of plants C. E. coli growing in the large intestine of humans D. Staphylococcus epidermidis growing on the skin Symbiotic relationships are common among microorganisms. Normal flora microbes associated with the human body typically represent either commensal or mutualistic relationships. In a commensal relationship, one organism benefits while the other is unaffected. In a mutualistic relationship, both organisms benefit. The third type of symbiosis is parasitism, in which one organism benefits at the expense of the other. In nature, it is possible to find examples of all three types of symbiosis.

BOD is highest during which of the following phases of municipal wastewater treatment? A. primary treatment B. sludge treatment C. secondary treatment D. chemical treatment

A. primary treatment BOD is highest during primary treatment, which removes only 25 to 35% of the BOD in the water.

Which aquatic zone in a lake will have the highest nutrient levels and therefore the densest microbial populations? A. the littoral zone B. the sediment zone C. the limnetic zone D. the benthic zone E. the profundal zone

A. the littoral zone

After their field trips to the cheese factory and the winery, Alexis and her classmates are asked to discuss what they have learned about the microorganisms in these processes. They are also asked to do a group presentation on a beneficial aspect of microbes in an area other than food microbiology. Which of the following could Alexis's group use as the topic for their group project? Check all that apply A. The eutrophication of bodies of water, such as lakes and rivers, due to the addition of nitrates and phosphates results in increased growth of algae and phytoplankton. B. Microorganisms, primarily bacteria and fungi, return carbon dioxide to the atmosphere when they decompose organic wastes and dead plants and animals. C. Bacteria can be used to remove toxins from underground wells, chemical spills, toxic waste sites, and oil spills, such as the massive oil spill in the Gulf of Mexico in 2010.The bacterium D. Escherichia coli synthesizes vitamin K and some B vitamins in the large intestine of humans.

B. Microorganisms, primarily bacteria and fungi, return carbon dioxide to the atmosphere when they decompose organic wastes and dead plants and animals. C. Bacteria can be used to remove toxins from underground wells, chemical spills, toxic waste sites, and oil spills, such as the massive oil spill in the Gulf of Mexico in 2010.The bacterium D. Escherichia coli synthesizes vitamin K and some B vitamins in the large intestine of humans. Microorganisms are often given a bad reputation because of their ability to cause disease or to spoil food and beverages. In reality, only a small percentage of microbes is actually pathogenic or causes spoilage. Beneficial microbes do exist! They are necessary for nutrient cycling between organisms and the environment. They can be used in bioremediation to clean areas that have been contaminated. They are also part of the human intestinal flora and produce essential vitamins. These are just a few examples. There are many environmental, applied, and industrial applications for microbes. The key is to identify which ones to use in these various processes.

Jamie is able to identify a new species based on DNA sequencing in a relatively short amount of time. Now the obstacle is to grow it in the laboratory. Knowing that the microbe was found in nature near a hydrothermal vent, Jamie sets up a specialized vessel to mimic those conditions. Several months later, she finds some patchy growth. She isolates some of the organisms and processes them for scanning electron microscopy. Based on her morphological results, she determines that the organism is most likely in the Domain Archaea. Jamie's images look very similar to image A, which, based on DNA sequencing, is a relative of her novel species. Jamie classifies the novel organism as a member of the Domain Archaea. Given that the organism was isolated near a hydrothermal vent, she is curious about its role in biogeochemical cycling. Which of the following situations is an example of biogeochemical cycling? Select all that apply. A. Bacteria were added to the Gulf of Mexico to degrade oil that was spilled after a deep-water drilling accident. B. Photoautotrophs incorporate carbon dioxide into organic matter using energy from sunlight. C. Plants and bacteria incorporate sulfates to become part of sulfur-containing amino acids for humans and other animals. D. Some microbes decompose proteins from dead cells and waste products to their amino acid subunits, which are ultimately converted into ammonia.

B. Photoautotrophs incorporate carbon dioxide into organic matter using energy from sunlight. C. Plants and bacteria incorporate sulfates to become part of sulfur-containing amino acids for humans and other animals. D. Some microbes decompose proteins from dead cells and waste products to their amino acid subunits, which are ultimately converted into ammonia. Biogeochemical cycling results in the oxidation and reduction of elements by microorganisms to meet their metabolic needs. Carbon, nitrogen, sulfur, and phosphorus are elements that are essential to life on Earth, and they must be recycled.

The presence of which of the following can substitute for nitrogen fertilizers in legume crops? A. Azotobacter B. Rhizobium C. Bacillus D. Clostridium

B. Rhizobium All of these genera are nitrogen-fixing bacteria, but only Rhizobium is commonly associated with the roots of legume crops and can take the place of nitrogen fertilizers.

Why is the pasta you buy from the grocery store shelf considered a nonperishable food? A. It was sterilized during preparation. B. The low moisture content prevents microbial growth. C. It has a low nutritional content. D. Various preservative chemicals are added. E. Microbes present in the pasta inhibit the growth of harmful microbes.

B. The low moisture content prevents microbial growth.

Please recall what you have learned about microbial metabolism and food processing methods and choose the best method for prevention of food spoilage for the food type below. (Soup) A. Use of salt or sugar to draw water out of foods (preservatives). B. Use of more than one food processing type (for example, canning and use of preservatives). C. Packaging into cans and jars and exposure to high heat under pressure (canning). D. Freezing and vacuuming to dry foods (lyophilization). E. High-heat treatment for a short period of time (pasteurization).

B. Use of more than one food processing type (for example, canning and use of preservatives).

Potable water is water that A. is transferred from one place to another. B. contains low amounts of microorganisms and is considered safe to drink. C. contains a dangerous number of microorganisms. D. contains biosensors. E. is considered safe to drink because it is completely sterile.

B. contains low amounts of microorganisms and is considered safe to drink.

Which of these foods will spoil the fastest? A. intact foods B. moist foods C. processed foods D. foods with a low pH

B. moist foods

Food microbiology applies to A. the control of microbial activity to prevent foodborne illness. B. the use of microorganisms to make food and the control microbial activity to prevent foodborne illness. C. using microbes to solve agricultural problems. D. the use of microorganisms to make food. E. using microbes to improve livestock and to solve agricultural problems.

B. the use of microorganisms to make food and the control microbial activity to prevent foodborne illness.

Which of the following results when ethanol is allowed to oxidize to acetic acid following the fermentation of fruit, grain, or vegetables? A. whey B. vinegar C. beer D. wine E. must

B. vinegar

In an ONPG/MUG test, both bottles exhibit a color. This result most accurately indicates which of the following? A. Viruses are present. B. A non-coliform is present. C. Escherichia coli is present. D. A coliform is present.

C. Escherichia coli is present.

Jamie, a 47-year-old environmental microbiologist, is having the best day of her life! She has just returned from a three-day oceanographic expedition exploring the biota of a recently discovered hydrothermal vent in the Pacific Ocean. Her preliminary results seem to indicate that the team has discovered a complete and novel vent ecosystem. Jamie can't wait to characterize the different vent species she has collected and identify the role each plays in the processes that sustain a community of organisms in such an extreme environment. Which of the following statements about extremophiles is FALSE? A. Extremophiles can be found in environments with high salinity, such as the Great Salt Lake, or with low temperatures, such as the Antarctic. B. Extremophiles can include members of the Bacteria or Archaea that live in extreme environments. C. Extremophiles are generally pathogenic to humans. D. Extremophiles use specialized enzymes in their metabolic pathways.

C. Extremophiles are generally pathogenic to humans. At this time, the extremophiles that have been identified are not pathogenic to humans. Most likely, extremophiles are too specialized for extreme environments to successfully adapt to the median temperature and neutral pH of the human body.C.

Please recall what you have learned about microbial metabolism and food processing methods and choose the best method for prevention of food spoilage for the food type below. (Cheese) A. Use of more than one food processing type (for example, canning and use of preservatives). B. Use of salt or sugar to draw water out of foods (preservatives). C. High-heat treatment for a short period of time (pasteurization). D. Packaging into cans and jars and exposure to high heat under pressure (canning). E. Freezing and vacuuming to dry foods (lyophilization).

C. High-heat treatment for a short period of time (pasteurization).

Which of the following microorganisms associated with food poisoning thrives in cold storage? A. Salmonella spp. B. Shigella spp. C. Listeria monocytogenes D. Clostridium botulinum E. Escherichia coli

C. Listeria monocytogenes

Which of the following is a nitrogen-fixing bacterium that forms associations with the roots of plants? A. cyanobacteria B. Azotobacter species C. Rhizobium species D. Clostridium species E. anaerobic Bacillus species

C. Rhizobium species

Another thermophile, Thermus aquaticus, was isolated from a hot spring in Yellowstone National Park. It is the source of the enzyme Taq polymerase, which is used in the molecular technique called polymerase chain reaction (PCR). PCR is used to amplify sequences of DNA. What extremophile characteristic of this enzyme makes it an essential component in a PCR reaction? A. Taq polymerase is stable under acidic or alkaline conditions. B. Taq polymerase is stable under extremely cold temperatures. C. Taq polymerase is heat-stable and can withstand high temperatures. D. Taq polymerase is stable in solutions that are extremely high in salt.

C. Taq polymerase is heat-stable and can withstand high temperatures. Taq polymerase is an enzyme isolated from a bacterium, Thermus aquaticus, normally found in environments with extremely high temperatures. This enzyme is extremely heat-stable and can withstand the temperatures used in PCR to denature the double-stranded DNA. Other industrial applications are being examined using proteins isolated from extremophiles because they can withstand environmental extremes that normally result in the denaturation, or complete unfolding, of a protein.

Why are "fortified" foods more likely to spoil than are unfortified foods? A. Vitamins are frequently contaminated by the microbes that produced them. B. The foods are fortified by the addition of vitamin-producing microbes. C. The added vitamins and minerals can promote microbial growth. D. The vitamins require a neutral pH environment, which is suitable for many microbes. E. Every step of modification or manipulation of food increases the chance for contamination.

C. The added vitamins and minerals can promote microbial growth.

In the previous question, you learned that adding starter bacterial cultures is a necessary part of the cheese-making process. In the production of red wine, the starter cultures are made up of yeasts rather than bacteria. In both cases, the microbes are used for their fermentation capabilities and the production of the final product. Which of the following choices best explains how the fermentation processes in these two organisms, although similar in nature, produce two very different products? A. The bacteria and yeast produce sugars as a metabolic by-product, giving the cheese and wine a sweet flavor and characteristic aroma. B. The bacteria produce alcohols as a metabolic by-product that give the cheese its characteristic flavor and aroma, whereas the yeasts produce acids that give the wine its characteristic flavor and aroma. C. The bacteria produce acids as a metabolic by-product that give the cheese its characteristic flavor and aroma, whereas the yeasts produce alcohols that give the wine its characteristic flavor and aroma. D. The bacteria and yeasts produce fats as a metabolic by-product that give the cheese and wine their characteristic flavor and aroma.

C. The bacteria produce acids as a metabolic by-product that give the cheese its characteristic flavor and aroma, whereas the yeasts produce alcohols that give the wine its characteristic flavor and aroma. The bacteria used in cheese production are lactic-acid-producing bacteria. This means that they can eat the lactose sugar in the milk and will produce lactic acid in the process. This acid creates an acidic environment that helps form the curd and will continue to lower the pH of the cheese as it ages. The longer the incubation time of the cheese, the higher the acidity and the sharper the taste of the cheese. The yeasts added during wine production are also used for fermentation, but the intended goal is to produce alcohol: specifically, ethanol. Other types of microbes can also be used in the production of wine. For instance, lactobacilli strains are used in secondary fermentation to convert malic acid into lactic acid. In general, these processes are controlled to improve a wine's flavor and quality; however, if a bottle of wine is exposed to air over a period of time, it can become contaminated with bacteria that convert ethanol to acetic acid. This would spoil the wine by turning it into vinegar. Who wants to drink vinegar at the end of a rough day?

Municipal water treated with chlorine compounds contains A. no endospores. B. no cysts. C. a decreased microbial load. D. no viruses. E. no bacteria at all.

C. a decreased microbial load.

Which of the following microorganisms can be used as a biological insecticide? A. Penicillium B. Pseudomonas syringae C. Escherichia coli D. Bacillus thuringiensis

D. Bacillus thuringiensis

Which of the following best describes the primary role of microorganisms in food production? A. Microbes are pathogens that can contaminate foods and make people sick. Outbreaks of E. coli and Salmonella are examples. B. Microbes are found in food that has spoiled. The microbes or the products they produced are what spoils the food. Spoiled milk is an example. C. Microbes are found in food that requires their metabolic products for flavoring. The use of molds to flavor cheese is an example. D. Some microbes are responsible for food spoilage, whereas others are used to increase the flavoring of the food or to produce the food product itself.

D. Some microbes are responsible for food spoilage, whereas others are used to increase the flavoring of the food or to produce the food product itself. Microorganisms play a variety of roles in pathogenesis, food production, food spoilage, nutrient cycling, decomposition, industrial production, and even the development of potential fuel sources. As you study microbiology, it is important to remember that only a small percentage of microorganisms actually causes human disease. Microbes are capable of beneficial roles as well!

Please recall what you have learned about microbial metabolism and food processing methods and choose the best method for prevention of food spoilage for the food type below. (Bacon) A. Freezing and vacuuming to dry foods (lyophilization). B. Use of more than one food processing type (for example, canning and use of preservatives). C. Packaging into cans and jars and exposure to high heat under pressure (canning). D. Use of salt or sugar to draw water out of foods (preservatives). E. High-heat treatment for a short period of time (pasteurization).

D. Use of salt or sugar to draw water out of foods (preservatives).

Agricultural runoff that deposits large amounts of phosphate into rivers and lakes results in which of the following? A. biomining B. anammox C. nitrification D. eutrophication

D. eutrophication Eutrophication is the overgrowth of microorganisms in lakes and rivers as the result of the increase in nutrients from agricultural runoff, particularly involving fertilizers rich in phosphate.

A new industrial park in your community dumps its wastewater into a large aerated pond, to which nutrients are added. The water from this pond makes its way into a nearby marsh, which eventually drains into a slow-moving stream. This is an example of A. artificial bioremediation. B. a method to make potable water. C. bioreporter use. D. natural bioremediation. E. natural fermentation.

D. natural bioremediation.

Which of the following is a specific example of bioremediation? A. the purification of water for drinking B. the treatment of wastewater C. the treatment of sludge D. the degradation of crude oil spilled into the Gulf of Mexico E. acid mine drainage

D. the degradation of crude oil spilled into the Gulf of Mexico

Along her tour, Julie noticed many types of cheeses that were being aged for texture and taste. In the processing of cheese there are many things that can be done to prevent the introduction of microorganisms. This same concept applies not only to cheese, but to wine, vegetables, and meat products. Based on the food that is being manufactured, various processes like pasteurization, chemical preservation, and radiation can all be used. All of these preservation methods take into consideration characteristics of microorganisms, such as the presence or absence of a cell wall, the role of osmotic pressure, their growth at preferred temperatures, and many other important characteristics.Please recall what you have learned about microbial metabolism and food processing methods and choose the best method for prevention of food spoilage for the food type below. (Peas) A. Freezing and vacuuming to dry foods (lyophilization). B. High-heat treatment for a short period of time (pasteurization). C. Packaging into cans and jars and exposure to high heat under pressure (canning). D. Use of salt or sugar to draw water out of foods (preservatives). E. Use of more than one food processing type (for example, canning and use of preservatives).

E. Use of more than one food processing type (for example, canning and use of preservatives).

Which of the following additives help preserve food as well as enhancing flavor? A. cinnamon B. salt C. garlic D. salt and pepper E. cinnamon, garlic, and salt

E. cinnamon, garlic, and salt

Which of the following methods of preserving food sterilizes it? A. canning B. drying C. lyophilization D. pasteurization E. gamma radiation

E. gamma radiation

During treatment of water to make it potable, about 90% of the microbes are removed A. by treatment with biosensors. B. in the sedimentation step. C. by treatment with chlorine or ozone. D. by preliminary fermentation. E. in the filtration step.

E. in the filtration step.

Pickling is an effective means of food preservation involving A. increasing pH. B. increasing salt concentration. C. reducing pH. D. increasing both salt concentration and pH. E. increasing salt concentration or reducing pH or both.

E. increasing salt concentration or reducing pH or both.

Which of the following pairs is mismatched? A. brandy; fruit juice B. vodka; potatoes C. beer; malt D. whiskey; cereal grains E. white wine; must

E. white wine; must

During her tour, Julie starts to notice a lot of equipment such as walk-in refrigerators, huge ovens, and industrial canners. She knows that a part of her inspection is to look at the factors that can affect food spoilage, so she starts to make a list of things she wants to come back to once the inspection begins. There are many factors, both internal and external, that can affect spoilage in food production. It is the responsibility of food manufacturers to know what these factors are and to make sure that everything that is made is in compliance. During Julie's study of microbiology, she learned about inherent properties of food, such as nutrient content, water activity, and pH, that play a role in food spoilage. There were also important external factors, such as how food is processed, handled and stored, that were critical to food spoilage and preservation. Please sort each of the following statements as being either an external or internal factor that affects the growth of microorganisms in food. Please recall from your reading the causes of food spoilage and how it can be prevented.

External Factors: *Temperature of food storage during processing. *Humidity of the storage environment *Presence of gases, such as CO2, during packaging *Preservatives, such as salt and sugar *Handling of food by manufacturers Internal Factors: *pH of the food *Presence of antimicrobial compounds *Nutrient content (Such as vitamins and minerals) *Moisture content or water activity *Protective structure of food, such as feathers, hide and skin

The Midwest is known for its contribution to the dairy industry. Fermented dairy products include milk, yogurt, and cheese. The fermentation process relies on lactic acid bacteria and pasteurization. Fermentation can vary based on what food is being produced, the type of bacteria used to produce lactic acid, and the time and temperature of pasteurization. It is important to the manufacturer to produce a product that won't spoil before it is packaged and sold and that won't result in disease for those who ingest and enjoy it. Julie, a food inspector for a local Michigan health department is going to a nearby cheese plant for a biannual inspection. When she gets there, she will take a tour of the plant and allow the operators to describe what makes their cheese so special. She will use what she understands about fermentation to inquire about their production practices. Please sort the following statements as being true or false regarding fermentation and its role in food production. Please recall the role that microorganisms can play in the production of foods.

Incorrect statement are: 1. Fermentation can be used only to make dairy products. 2. Only bacteria are used in the fermentation process. 3. Fermentation occur when, undesirable metabolic reaction allow for the growth of pathogens, or the presence of unwanted micro-organism in the food. Correct statement are: 1. Starter culture are used to initiate the process of fermentation. 2. Lactic acid is produced by certain micro-organism and that aids in fermentation. 3. Fermentation allow for sugar to be broken down or metabolized production. 4. Some grains, fruit, vegetables have their own microbes that facilitate fermentation

Match the following groups of extremophiles with the environment in which they live. Match the following terms with their definitions.

See Image Extremophiles are microbes that live in extreme conditions of temperature, acidity, alkalinity, or salinity. These organisms can be members of the Bacteria or Archaea, both of which are prokaryotic and have various metabolic processes. Thermophiles thrive at temperatures between 50 and 60 degrees C. Hyperthermophiles thrive at extremely high temperatures. Psychrophiles thrive at extremely cold temperatures. Acidophiles like pH values less than 7, whereas alkalophiles like pH values greater than 7. Halophiles like salt concentrations of greater than 25%. Research is ongoing to identify even more organisms that live in environments inhospitable to most other organisms.

During her inspection, Julie took many samples of the cheeses that were manufactured in her local plant back to the health department laboratories. She decided to pay particular attention to testing for the presence of microbial products in the cheeses. She will use a variety of tests depending on the sample, but these will most likely include the inoculation of selective and differential media to characterize the use of specific carbohydrates and the production of certain enzymes. Julie knows that since milk is used in the processing of cheeses, organisms like Salmonella enterica, Campylobacter jejuni, and Listeria monocytogenes can all be found in raw milk and dairy products. These microorganisms are introduced into the milk and other food products in many ways. Microorganisms are everywhere, and often when food products such as milk are collected and handled, these microorganisms are able to enter the food. In order to ensure the health of the millions of people every day, a food microbiologist like Julie ensures that food is kept in the best conditions during processing, packaging, and when it gets to stores for purchase. Please consider what you have learned about foodborne illness from the text, and choose the correct description of the term below that is best associated with foodborne illness.

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The United States leads the world in the making of cheese, producing millions of tons each year. What is the correct sequence of events in the production of cheese? Arrange in chronological order the following steps in cheese production.

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